It has been said that there are only three areas into which all conversation falls, people, events and ideas. Whether we ascribe to that view is another matter but Eleanor Roosevelt gave it particular pungency when she said "Great minds discuss ideas. Average minds discuss events. Small minds discuss people.”

The idea here is not so much to take up the point about conversation but rather to consider the power of ideas. In the dim and distant past it was believed that the world was flat. That was an idea that ruled the times for centuries and now we know differently. Tom Friedman may not agree but, of course, he is looking at the planet from a different perspective.

Another idea that ruled the times was that the planets revolved around the Earth. Copernicus replaced that idea with what we now know to be the situation - we and the planets revolve around the Sun. History is littered with such examples and the remarkable thing about some of these ideas is their power to occupy the mind and prevent it from seeing something as it really is. One might think of it as a form of mass chronic denial that for a period of time huge numbers of people can completely deny the fact that the idea in question just does not stand up to critical analysis.

One such idea that seems to hold sway today is that our activities are not having a material and/or deleterious impact upon the planet. One can think of this in various ways. The global population is expanding. It is estimated to be just shy of 7 billions now and could grow to 9 billions by 2050. Given that the planet is a finite resource this presents challenges as to how we will feed ourselves, where sufficient fresh water will come from, how we will manage the demands for energy including that from a depleting fossil fuel resource and a whole host of other issues. And we didn’t even mention climate change or global warming yet.

In last week’s The Economist magazine there was a rather sobering briefing entitled The Anthropocene. The thrust of the article is simply that we now appear to have moved out of a period of relative stability in the way that the planet works. This is the province of something called Earth-systems science and it examines how the planet has “worked” over very long periods of time, geologic time measured in the hundreds of millions of years. The notion is that we are now in the Anthropocene – the age of man – and we are not just spreading over the face of the planet but changing the way that it works.

Some of us will be familiar with Dr. James Lovelock and the Gaia Hypothesis. In simple terms this suggests that the Earth is a complex, living, self-regulating organism that operates to maintain the conditions for life on the planet, an homeostatis if you will. Of course when this new idea was promoted in the 1970s it was regarded as complete heresy. Lovelock and Copernicus had something in common.

But back to The Economist and the age of man. The suggestion is that we can now see clear evidence of the effect of man upon the Earth’s systems. Obviously advances in science and technology have played their part and we can now measure changes in these systems and two in particular - the natural cycles related to nitrogen and carbon.

Take the nitrogen cycle as an example. In 1890 scientists worked out that most of the atmospheric nitrogen (100 megatonnes) was converted into a useable form by plant life. Small amounts were converted by lightning (5 mt) and by the nitrogen fixing capabilities (15 mt) of farm crops. As of 1990, a mere 100 years later the plant life contribution had dropped to 89 mt and the farming contribution had burgeoned from 15 to 118 mt. What brought this about was the invention of the Haber-Bosch process which enabled atmospheric nitrogen to be used to create ammonia which, in turn, was used to create fertilizers and explosives. What stimulated this invention is an interesting digression that we will have to leave for another time.

However, per Wikipedia, fertilizer generated from ammonia is responsible for sustaining one-third of the Earth's population. Furthermore it is estimated that half of the protein consumed by human beings globally is reliant upon nitrogen fertilizers that were originally fixed by the Haber process. We know some of the effects of the application of such fertilizer. In just one example it leaches out of the soil and contaminates the Mississippi River to such an extent that at a certain time of the year the waters from the river create a hypoxic zone in the Gulf of Mexico that is the size of the state of New Jersey. Most life forms perish in this zone and have to regenerate on an annual basis. There are dozens of other examples of the impact of just this one chemical compound.

The point is that through man’s ingenuity we have developed a capacity to make and use atmospheric nitrogen at a much greater rate than it can be recycled by nature’s processes. This is unsustainable and it is changing the way the planet works and in ways we do not fully understand.

Something similar is occurring with the carbon cycle. We are emitting far more carbon dioxide into the atmosphere than Mother Nature can recycle at her own pace. By some estimates it could take 1,000 years or more for the planet to assimilate these elevated levels of this gas and that assumes that we do not continue to add to them.

The issue is that the idea that we can use and abuse the planet and its resources as we see fit is patently wrong. As long as we think that we can continue to operate as we do with impunity we are headed for trouble. We need to come to the understanding, and relatively quickly, that we are but one thread in the complex web of life that exists upon this planet. If we are to develop a sustainable way of life here in the US, and elsewhere for that matter, some new ideas are desperately needed.